Method of processing phosphate ore to recover metallic minerals



RECOVER METALLIC lVIlNERALS nited States Patnt Ira Milton Le Baron, Evanston, Ill., assigner to Interi national Minerals & Chemical Corporation, a corporation of New York Application July 19, 1957, serai No. 673,062

9 claims. (cl. 20s- 166) This invention relates to the recovery of certain valuable mineral constituents vfrom ores containing the same. More particularly, the invention relates to the recovery of phosphate values as well 'as metallic minerals such as ilmenite, rutile, zircon, monazite, and other certain socalled heavy minerals from ores containing substantial amounts of phosphate rock and siliceous material.

Traces of certain metallic Vminerals including ilmenite, rutile, monazite, sillimanite aswell as minor amounts of garnet, tourmalineare known to occur in association with the silica-phosphate rock in the Florida phosphate eld. As distinguished from their occurrence in various Florida and Australian sands, the heavy minerals are present in this phosphate matrix in quantities of less Vthan about 0.1% by weight. By subjecting phosphate material to flotation operations, for therecovery of the phosphatic values contained therein, according to the notation processes heretofore in use, the metallic mineral content of the phosphate ore may be gathered together intoa heavy mineral concentrate having a heavy mineral content of 2 to 4% by weight. In the past, silica concentrate produced in the flotation of phosphate ores has been discarded. The composition of the silica concentrate produced by this method averages about 60 to 70% by weight of silica, about 10 to 20% by weight of tricalcium phosphate, the remainder consisting of the aforementioned heavy mineralv together with other gangue impurities. A silica fraction containing only 2 to 4% by weight of metallic mineral is not commercially adaptable to industrial recovery processes and requires elaborate notation operation with consequent capital investment to convert the heavy minerals to a concentrateof 40% or higher heavy mineral content to make the concentrate adaptable -to industrial recovery processes currently in use. v

It is a primary object of this invention to provide a new and novel combination of processing steps, eliminating the disadvantages and shortcomings of processes heretofore in use.

It is an object of this invention to provide a novel process for the recovery of metallic mineral values from phosphatic ores by subjecting the phosphatic ores to otation to recover -three products, each of which will be described as to its processing steps.

It is another object of this invention to provide `a novel process whereby the phosphate in the concentrate is recovered in higher purity than is attained `in the present phosphate otation operation and with more complete recovery and the mineral values recovered in commercially acceptable concentration.

It is still a further object of this invention to provide a process whereby the phosphate ore is subjected to a highly selective rougher separation initially and thereafter the predominantly silica fraction which formerly was discharged to waste, and a silica fraction obtained in the production of a nal phosphate concentrate are combined to the process in a novel Way for the recovery f the heavy minerals therein.

ice

These and other objects of the invention are accomplished by subjecting a linely divided phosphatic-siliceous ore which contains base metal oxide type metallic minerals to a rst or rougher otation operation with anionic or fatty acid reagent conditions being designed for high selectivity and recovery as regards the phosphate component of the ore. From this rougher flotation operation, there is also recovered a silica fraction and an intermediate fraction which may be designated a middling fraction or a secondary concentrate. The primary phosphate concentrate is then subjected to an upgrading operation generally utilizing cationic otation reagents "(designated as the number 2 cationic otation hereinafter) without further intermediate processing other than sulfuric acid scrubbing to` remove the anionic agent. The middling fraction is subjected to additional stages of anionic otation to recovera phosphate concentrate which is subjected to a cationic flotation to produce a phosphate undertlow which is combined with the primary phosphate concentrate as feed to the number 2 cationic flotation and a froth ,product which is combinedwith the froth from the number 2 cationic flotation so'that the froth product may be de-reagentized for processing by gravity separation means to produce a high purity heavy mineral bulk concentrate and a silica plus phosphate fraction processa-.

ble by notation means, either anionic or cationic, to produce a throw-awayk silica tail and a phosphate concentrate which may be kept separate or recycled, for example, to the feed to the number 1 cationic flotation operation.

In the instant process, no special attempt is made to float the heavy mineral.

In carrying out the process, the phosphatic ore is subjected to a Washing operation in order to remove slimes and organic matter. The Washed rock, in aqueous pulp form, is subjected to screening or hydraulic sizing where by the pebble or larger particles of phosphate rock are segregated from material which is approximately -1 mm. size. The -1 mm. size material is subjected to fur ther washing for complete desliming, which desliming is produced by separating the mesh size material from the +150 mesh size material. The +150 mesh size material, called sand, is subjected to a screening operation to produce a +35 mesh size fraction which is passed to spiral operations for concentrations and a -35 mesh size fraction which is the feed to the notation circuit. The major portion, on the order of 70 to 80% of the heavy mineral in the phosphate ore, reports in this -35 +150 mesh size fraction.

In the phosphate flotation operation, the -35 mesh fraction of the ore is mixed with anionic reagents which have an ainity `for phosphate material and the heavy mineral. The reagentized mixture is subjected to otation under conditions giving high recovery and selectivity. In order to Aattain this selectivity, the general practice is to reduce the amount of anionic reagents used in this rougher notation. If, for example, tall oil is used for the anionic otation, the quantity of this material used as reagent is generally between about 1 and 1.25 pounds of tall oil per ton of ore feed. When effecting ilotation under conditions for high selectivity, the amount of this tall oil reagent would be reduced to generally between about 3A to 1 pound per ton of feed. There are several ways in which the oatcell operation can be performed to produce a product with high selectivity. Generally, the procedure is to have so-called split'cell and to give the reagentized ore in these cells a shorter retention time. In such a cell arrangement, feed flows from one cell to the other as a pulp, the froth brought tothe top in the first part of the split cell arrangement being the phosphate concentrate of highest purity. The product obtained in the third or fourth or fifth section of, for example, split cell, can be recovered as the middling or number two concentrate for further processing since' it will have a lower BPL content than the concentrate removed in the first section of they split cell. IThe -rprimary phosphate concentrate or material of highest BPL content is not subjected to further anionic flotation operation but is washed with sulfuric acid and given a washing with water to rendei the slurry substantially neutral and then subjected to a cationic flotation operation. l l e p Number 2 phosphate concentrate or middling fraction from the rougher flotation operation is generallyl subjected to reflotation without further reagentiing in socalled' cleaner and recleaner operations. These flotation operations' are anionic tlotations' andare performed at. approximately the same pH, i.e.,. 8` 'to 3, as is generally utilized in the rougherl flotation. Silica tail fraction from the cleaner flotation operation usually i'scon`1 bined with the yrx'gher'til fraction beingl lsent to the scavenger flotation circuit. Tail fractionfrom therecleaner, operation is vrecycled to` the feed to the cleaner cell or to the rougher' feed depending upon the BPL content of this underflow product.-

Recleaner or secondary phosphate concentrate is scrubbedwith mineral acids, such as sulfuric acid, hydrochloric acid, and the like,fto remove the anionic reagents therefrom and the washedy concentrate is subjected to asilica flotation operation with cationic or nitrogenous ion agents.'

Anionic or carboxyl containing negative ion agents which are useful` in the rougher,cleaner and recleaner stages of phosphate concentration are,l for example, higher unsaturated fatty acids, i.e., oleic, linoleic, and abeitic acids, nitroresin acid, tall oil, naphthenic acid, alkyl sulphonated fatty acids, acid ester of`high molecular weight aliphatic alcohols, and the soaps of such materials. Included within the term soaps of such negative ion or anionic type reagents? are the alkali methyl and' alkaline earth metal soaps such as sodium, potassium, aluminum, calcium, and magnesium soaps. Soaps may also be formed-by reacting such reagents with ammonia or aqueous'solutions thereof.' The -35 mesh size particles are reagentized with one or more of these reagents in the presence of water by agitating the mixture at a solids content between about.50'%v andabout 75% by weight. Reagents are added tothis floating operation in varying quantities but n-general, for fatty acids, the amount of` reagent required generally falls'between about 0.75 pound and about 2 pounds of reagent per ton of ore. Following the slurrying operation, the reagentized mixture is diluted to a concentration suitable for introduction in the flotation cell, generally to a solid content in the range of between about 20% andabout 30% solids. In the reagentizing cell, a froth is formed which carries the phosphate and heavy mineral to the top where this fraction is removed by overflow. This fraction, overflowing from the anionic flotation cell, is recovered for further processing as follows: The anionic reagents are removed from the solids by scrubbing with'sulfuric acid. After' scrubbingV the solids are washed'free' kof reagents and acid by agitation with`wa`shl water. The washed solids are then dewatered to a solids content of the order of 40 to 70% solids and then cationicflotation reagent added while the mixtureis being agitated. This cationic flotation reagent is designed to remove'theminor components of the phosphate concentrate, i.e., silica. Useful cationicor positive ion reagents for this stage of the flotation procedure are the nitrogenous positive ion agents'such as the higher molecular weight aliphatic amines'containing at least one alkyl group having l2 to'20 carbon atoms and their water solubleaddition salts with mineral and organic acids, estersbf amino alcohol's'with higher molecul'ai'weight-fatty. acids, and higher alkyl substituted isoreas' 'and their water soluble salts, high molecular weight aliphatic Quaternary 4 monium bases and their Water soluble salts, alkyl substituted peridinium and quinolineum water soluble salts and the like.

In this novel process, phosphate concentrate obtained as the underflow of the cationic flotation is dewatered and combined with acid scrubbed primary phosphate concentrate toprovide a feed for the secondary cationic flotation operation. Products of the secondary cationic flotation are a final phosphate concentrate of about 72% to 78% bone phosphate of lime.

Tail products from the flotation operation of both the primary and secondary phosphate concentrates with positive ion agents consisting of phosphate, silica and heavy minerals are freed of the nitrogenous positive ion reagent by any one of a number ofy treatments. The mixture may be dereagentized by treating it with acidic material such as mineral acids, for example, sulfuric acid or hydrochloric acid, or the amine' reagent may bel removed by treatingv the slurrymixture by scrubbing with agents such as sodium hypochlorite. j The dereagentized mixture of silica, phosphate and heavy minerals is next subjected to separation on the basis of specific gravity differences of the various materials. This specific gravity separation may be effected jacent to the outer perimeter of the trough and are rcon the Wilfley table but is preferably carried out on spiral where a slurry ofthe mixture is flowed by gravity through a trough having a spiral or elliptical pass adapted for drop out of the heavy mineral'through drop out ports along the inside edge of the trough whereas the lighter specific gravity material continues to flow in a path adcovered from the bottom of the spiral. Specific gravity differences between the heavy minerals and silica and phosphate are such that in a specific gravity separation a concentrate of heavy minerals may be produced of between about 80% andl 95% by weight of heavy minerals. The silica and phosphate fraction from this separation can be subjected to a flotation operation, the type of flotation being-dependent upon the relative proportion of silica and phosphate. This flotation operation will produce` a silica tail anda low grade phosphate concentrate. The silica and phosphate fraction instead of being treated separately may ,also be recycled to the middling amine flotation operation.

The invention will beV more fully understood from a study of the figure which illustrates the preferred embodiment of this process. Referringlto the llowsheet, deslimed phosphate ore of about .35 mesh -l-lSO mesh size is indicated by the numeral 10. This material is mixed with flotation agentcomposition containing negative ion agents such as tall oil and delivered to a flotation operation 12. In flotation operation 12 there is produced three products: a middling fraction 13, a silica tail fraction 14, and a'primary phosphate concentrate 15. Middling fraction 13 is subjected to further concentration in a cleaner flotation stage 16 in which there is produced a cleaner concentrate and a tail fraction 17. Tail fractionI 17 is combined with silica tail fraction 14 and subjected to scavenger flotation operation 18 wherein is produced a silica tail IQAwhich vis discharged to waste. The phosphate fraction 20 recovered in` this scavenger flotation operation is recycled'for combining with the feed to the cleaner flotationy operation 16.' Concentrate from cle'aner'llotation operation 16 is` subjected to a` recleaner flotation operation 21. Iny the recleane'r there s produced a tail fraction 22 which is recycled for combining with the feed to thev cleaner flotation operation 16.v Concentrate recovered inthe 'frecleaner operation 21 designated 23,I is mixed' with sulfuric acid-24 and passed to a scrubber 25 where `the negative'ion agents are removed. After scrubbing, Vthe'fmixture' is washed' in washing operationtZ "to render theslu'rry free of lreagent and`acid.' Washed' co'r'i'c'entr'a'te is'mixd with positive ion agent '27 `and passed to'a flotatioi'opera'tionZS which produces a tail fraction 29 and a phosphate concentrate 30.

Primary phosphate concentrate 15 is mixed with sulfuric acid 31 and passed to a scrubbing operation 32 followed by washing operation 33; Washed concentrate is reagentized by mixing into the washed concentrate positive ion agent 34 and the reagentized mixture combined with concentrate from the flotation operation 28. This mixture is fed lto a flotation operation 35 in which there is produced a final phosphate concentrate 36 and a tail fraction 37. Tail fractions 37 and 29 are combined and passed to reagent removal stage 38 wherein the positive ion agents are removed. The silica fraction after reagent removal, is passed to a gravity `separation stage 39 where there is produced a heavy mineral bulk concentrate 40 and a silica plus phosphate fraction 41. This silica and phosphate fraction 41 is reagentizedwith ilotation reagent 42 and subjected to a otation operation 43 in which there is`produced a silica tail fraction 44 and a phosphate concentrate 45. A

The nature and character of the invention isT further illustrated by the example which is given by wayof illustration and without any intention that the invention be limited thereto.

Example A phosphaterock of the type found in phosphate pebble fields of Florida is subjected to a washing operation in order to remove slirnes and all organic matter. The washed rock in an aqueous pulp is subjected to a screening or hydraulic sizing operation whereby the larger particles of rock are segregated from material whichl is approximately -35 mesh standard screen4 size. The 35 mesh material is classified to produce a fraction of -35 +150 mesh size. This fraction is reagentized in an aqueous pulp containing about 60% solids with about 0.8- poundof a reagent comprising about 88% tall oil and about 12% kerosene per ton of ore treated. To

this mixture is added about 2 pounds of fuel oil and p suicient caustic soda to give the mixture a pH of between 8 and 9. The resultant pulp is diluted with water to a `solids content of about 30% by weight and subjected to a flotation operation in a Fagergren machine from which is recovered a float product containing approximately 60% tricalcium phosphate, about 30% silica,

and about 1.0% of metallic minerals.

This phosphate product is scrubbed with about to 8 pounds of sulfuric acid (60 B.) to remove reagents therefrom. The acid treated slurry is washed with water until it is substantially neutral. The aqueous pulp at a solids content of about 30% is reagentized with 0.5 pound/ton of slurry solids of a mixture of long chain aliphatic amine acetate salt, the latter comprising a mixture of about 73% monooctadecyl amine and about 24% monohexadecyl amine, together with small quantities of secondary and tertiary amines. To this mixture was added about l pound of kerosene/ ton of solids and suflicient caustic soda to adjust the pHV of the mixture to between 7.5 and 8.0, i.e., about 0.25 pound solid caustic/ ton of solids.

The amine reagentized material, when combined with amine otation underflow products hereinafter described, is subjected to agitation and aeration in a Fagergren machine. The froth product from this No.2 amine ilotation contains approximately 30% silica, 50% BPL and 2.9% metallic minerals by weight.

Middling fraction obtained in the numbers 3 and 4 compartments of a 4 pocket machine, for example, of the rougher otation cell, assayed 39% BPL, 29.5% insolubles, and .4% metallic minerals. f

This froth product was reoated in a cleaner cell, a silica underow sent to the scanvenger section assaying 9.3% BPL. v i- Cleaner concentrate was again iioated in a recleaner `operation producing a tail fraction asisaying 20.4% BPL.

Recleaner concentrate assayed 62.4% BPL and 20.9%

tent slurry and the slurry scrubbed with 1 pound of sodium hypochlorite/ton of solids and then washed with water.

Hypochlorite scrubbed solids are diluted to about 25% solids slurry and the slurry-flowed at a rate of l ton of solids/hour over a Wilfley shaking table.

Products from the tableassayed as follows:

Percent Percent Percent BP Ins (Calc.)

Tail 16. 53 78. 4 0. 72 Concentrate 2. 89 96. 3 93. 7

Having thus described this invention, what is desired to be secured by Letters Patent is:

l. In a process for separately recovering phosphate and-heavy minerals from a phosphate ore comprised thereof with silica, wherein said ore is subjected to flotation to segregate a phosphate fractionand a heavy minerals fraction, and the heavy minerals fraction is subjected to gravity separation to produce a heavy minerals concentrate, the improvement which comprises subjecting 4the ore innely divided form to anionic ilotation with an anionic dotation reagent having an ailinity for phosphate to produce an anionic float concentrate predominating` in phosphate and containing silica and heavy numerals, an anionic middling fraction containing silica, heavy minerals, and phosphate, and anv anionic tailing fraction predominating in' silica and containing heavy minerals and phosphate, subjecting said middling fraction to at least one anionic cleaner otation step to produce a cleaner otation concentrate, separately scrubbing said anionic oat concentrate and said cleaner oat concentrate to remove amonio reagents therefrom, subjecting said dereagentized cleaner float concentrate to a first cationic ilotation with a cationic otation reagent having an ainity for silica to produce a first cationic float concentrate predominating in silica and containing phosphate and heavy minerals, and a rst cationic underflow product containing silica and predominating in phosphate, reagentizing the dereagentized anionic ilotation concentrate with a cationic otation reagent having an affinity for silica, admixing the cationic reagentized anionic concentrate with said irst cationic underow product, subjecting the resulting mixture to a second cationic ilotation step to produce `a second cationic oat concentratev predominating in silica and containing phosphate and heavy minerals and a second cationic underflow product, the latter being a highly'concentrated phosphate product, admixing said first cationic float concentrate and said second cationic oat concentrate, and removing cationic reagent from solids in the resulting mixture, whereby said mixture is rendered amenable to said gravity separation to produce a heavy minerals concentrate.

2. In a process for separately recovering phosphate and heavy minerals from a phosphate ore comprised thereof with silica, wherein said ore is subjected to ilotation to segregate a phosphate fraction and a heavy minerals fraction, and the heavy minerals fraction is subjected to gravity separation to produce a heavy minerals concentrate, the improvement which comprises subjecting the ore in nely divided form -to anionic flotation with an anionic flotation reagent having an afiinity Vfor phosphate to produce an anionic float concentrate predominating in phosphate and rcontaining silica and heavy minerals, an anionic niiddling fraction containing silica, heavy minerals, and phosphate", and an anionic tailing fraction predominating in silica and'v containing heavy minerals and phosphate, subjecting said middling fraction to an anionic cleaner flotation s'tep to produce a cleaner float concentrate and a cleaner failing fraction,l combining said cleaner tailing fraction with said anionic' failing fraction and subjecting the combined failing fractions to a scavenger flotation step to produ'c a scavenger float concentrate and a scavenger tailing fraction, recycling said scavenger float concentrate to said cleaner flotation step, subjecting said cleaner float concentrate to a recleaner flotation step to produce" ra rcle'aner float concentrate and a recleaner failing fraction, recycling" said recleaner failing fraction to said cleanerv flotation step, separately scrubbing said anionic float concentrate and said recleaner float concentrate to remove anionic reagent therefrom, subjecting said dereagentized recleaner float concentrate to a first cationic flotation witha cationic reagent having an affinity for silica to produce a first cationic float concentrate predominating in silica and containing phosphate and heavy minerals and a first cationic underflow product containing silica and predominating in phosphate, reagentizing the dereagentized anionic flotation concentrate with a cationic flotation reagent having an aflinity for silica, admixing said cationic reagentized anionic concentrate with said first cationic underflow product, subjecting the resulting mixture to a second cationic flotation step to produce a second cationic float concentrate predominating in silica and containing phosuhate and heavy minerals and a second cationic underflow product, the latter being a highly concentrated phosphate product, admixing said first cationic float concentrate and said second cationic float concentrate, removing cationic reagent frornthe solids in the resulting mixture, whereby Vsaid mixture is rendered amenable to said gravity separation to produce V'a heavy minerals concentrate.

3. The method of recovering mineral values from a phosphate ore containing silica and heavy minerals which comprises subjecting the ore in finely divided form to anionic flotation with an anionic flotation reagent having an affinity for phosphate to produce an anionic float concentrate predominating in phosphate and containing silica and heavy minerals, an anionic middling fraction containing silica, heavy minerals, and phosphate, and an anionic tailing fraction predominating in silica and containing heavy minerals and phosphate, subjecting said middling fraction to at least one anionic ycleaner flotation step to produce a cleaner flotation concentrate, separately sembbing said anionic float concentrate and said cleaner float concentrate to remove anionic reagents therefrom, subjecting said dereagentized cleaner float concentrate to a hrst cationic flotation with a cationic flotation reagent having an affinity for silica to produce a first cationic float concentrate predominating in silica and Acontaining phosphate and heavy minerals and a first cationic underflow product containing silica and predominating in phosphate, reagentizing the dereagentized anionic flotation concentrate with a cationic flotation reagent having an aflinity for silica, admixing the cationic reagentized anionic concentrate with said first cationic underflow product, subjecting the resulting mixture to a second cationic flotation step to produce a second cationic float concentrate predominating in silica and containing phosphate and heavy minerals and a second cationic underflow product, the latter being a highly concentrated phosphate product, admixing said first cationic float concentrate and said second cationic float concentrate, removingV cationic reagent from solids in the resulting mixture lof' 'cationic float concentrates, subjecting theder'e'agentized mixture of cationic float concentrate to a separation based upon differences in specific gravity to produce a heavy minerals concentrate and a fraction containing phosphate and predominating iny silica, reagentizing said fraction containing phosphate and silica'with ananionic flotation reagent, subjecting the reagentizd fraction' to anionic flotation to recover a siliceous' underflow product and a phosphatic float concentrate, and recycling said phosphatic float ccncentrate to said first cationic flotation step.

4. The method of recovering mineral values from a phosphate ore containing silica and heavy minerals which comprises subjecting the ore in finely divided form to anionic flotation withan anionic flotation reagent having an affinity for phosphate to produce an anionic float concentrate predominatng in phosphate and containing silica and heavy minerals, an anionic middling fraction containing silica, heavy minerals, and phosphate, and an anionic failing fraction predominating in silica and containing heavy minerals and phosphate, subjecting said middling fraction to at least one anionicv cleaner flotation step to produce a cleaner flotation concentrate', separately scrubbing said anionic float concentrate and said cleaner float concentrate to remove anionic reagents therefrom, subjecting said dereagentized cleaner float concentrate to a first cationic flotation with a cationic flotation reagent having an affinity for silica to produce a first cationic float concentrate predominating in silica and containing phosphate and heavy minerals and a first cationic underflow product containing silica and predominating iii phosphate, reagentizing the dereagentized anionic flotation concentrate with a cationic flotation reagent having an affinity for silica, admixing the cationic reagentiz'ed anionic concentrate with said first cationic underflow product, subjecting said ymixture to a second cationic flotation step to produce a second cationic float concentrate predominating in silica and containing phosphate and heavy minerals and a second cationic underflow product, the latter beihg a highly concentrated phosphate product, admixing said first cationic float concentrate and said second cationic float concentrate, removing cationic reagent from solids in the resulting mixture of cationic float concentrates, and subjecting the dereagentized mixture of cationic float concentrates to a separation based upon differences in specific gravity to produce a heavy minerals concentrate and a fraction containing phosphate and predominating 'in silica, reagentizing said fraction 'containing phosphate and silica with a cationic flotation reagent, subjecting the reagentized fraction to cationic flotation to recover a siliceous float product and a phosphatic underflow product, and recycling the said phosphate underflow product to said first cationic flotation step.

5. The method of Vrecovering mineral values from a phosphate ore containing silica and heavy minerals which comprises subjecting the ore in finely divided form to anionic flotation with an anionic flotation reagent having an affinity for phosphate to produce an anionic'float concentrate predominating in' phosphate and containing silica and heavy minerals, an anionic middling fraction containing silica, heavy minerals, and phosphate, and an anionic tailing fraction predominating in silica and Vcontaining heavy minerals and phosphate, subjecting said middling fraction to at least vone anionic cleaner flotation step to produce a cleaner flotation concentrate, separately scrubbing said anionic float concentrate and said cleaner float concentrate to remove anionic reagents therefrom, subjecting said dereagentized cleaner float concentrate to a first cationic flotation with a cationic flotation reagent having an affinity for silica to produce a first cationic float concentrate predominating in silica and containing phosphate and heavy minerals and a first cationic 'underflow product containing silica and predominating in phosphate, reagentizing the dereagentized anionic flotation concentrate with-a cationic -flotation reagent having an affinity for silica, admixing the cationic reagentized anionic concentrate with said fir/st cationic 'undeifiowproduch -subjecting the resulting fr'rxtn're to' 'a second vcationic flotation step to produce a second cationic float concentrate pre'- dominating in silica and containing phosphate and heavy minerals and a second cationic underow product, the latter being a highly concentrated phosphate product admixing said first cationic float concentrate and said second cationic float concentrate, removing cationic reagent from solids in the resulting mixture of cationic float concentrates, and subjecting the dereagentized mixture of cationic oat concentrate to a separation based upon diiierences in specific gravity to produce a heavy minerals concentrate and a fraction containing phosphate and predominating in silica, and recycling said fraction containing phosphate and silica to said rst cationc otation step.

6. The method of claim 5 wherein said anionic otation reagent is tall oil, and said anionic otation is carried out at a pH of between about 8 and about 9.

References Cited in the tile of this patent UNITED STATES PATENTS Hunter et al. June 12, 1956 Duke et al. July 10, 1956 OTHER REFERENCES Engineering and Mining Journal, vol. 151, issue 8, pages 87, 88, 89, published August 1950.

UNITED STATES? PATENT oTTIcE cEnTIFIcATE oF coRnEcTIoN Patent' No. 914,173 November 24, 1959 IraiMlton Le Baron It is hereby certifi ed that error` appears in the printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 4, line 25, strike out "jacent toI the outer perimeter of the trough and are r.e"; column g5, line 72, for

l Signed and sealed this 4th day of October 1960..

y (SEAL) 'Atviest:

KARL H. AXLINE 'y p ROBERT c. wATsoN Attestngjroffce'r Comasioner of Patents 

1. IN A PROCESS FOR SEPARATING RECOVERING PHOSPOHATE AND HEAVY MINERALS FROM A PHOSPHATE ORE COMPRISED THEREOF WITH SILICA, WHEREIN SAID ORE IS SUBJECTED TO FLOTATION TO SEGREGATE A PHOSPHATE FRACTRION AND A HEAVY MINERAL FRACTION, AND THE HEAVY MINRALS FRACTION IS SUBJECTED TO GRAVITY SEPARATION TO PRODUCE A HEAVY MINERALS CONCENTRATE, THE IMPROVEMENT WHCH COMPRISES SUBJECTING THE ORE IN FINELY DIVIDED FOPRM TO ANIONIC FLOTATION WITH AN ANIONIC FLOTATION REAGENT HAVING AN AFFINITY FOR PHOSPHATE TO PRODUCE AN ANIONIC FLOAT CONCENTRATE PREDOMINATING IN PHOSPHATE AND CONTAINING SILICA AND HEAVY MINERALS, AN ANIONC MIDDLING FRACTION CONTAINING SILICA, HEAVY MINRALS, AND PHOSPHATEAND AN ANIONIC TAILING FRACTION PREDOMINATING IN SILICA AND CONTAINING HEAVY MINERALS AND PHOSPHATE, SUBJECTING SAID MIDDLING FRACTION TO AT LEAST ONE ANIONIC CLEANER FLOTATION STEP TO PROUCED A CLEANER FLOTATION CONCENTRARE, SEPARATELY SCRUBBING SAID ANIONIC FLOAT CONCENTRATE AND SAID CLEANER FLOAT CONCENTRATE TO REMOVE ANIONIC REAGENTS THEREFROM SUBJECTING SAID DEREAGENTIZED CLEANER FLOAT CNCENTRATE TO A FIRST COATIONIC FLOTATION WITH A CATIONIC FLOTATION REAGENT HAVING 